Waterfall Software Development Methodology: Everything You Need To Know

The Waterfall model of software development, one of the earliest formalized approaches, revolutionized how software projects were led. Derived from manufacturing and construction, Dr. Winston W. Royce in 1970 discussed its feasibility and incorporated it into software engineering. Its linear, sequential approach, where progress flows steadily downwards through phases, provided structure and clarity in an era when software development was still in its infancy.

However, as software projects became more complex and dynamic, the rigid nature of the Waterfall model became a limitation. Agile methodologies emerged and began offering more flexibility. The shift rendered the Waterfall model less relevant for modern projects, dictated by adaptability and rapid response to changing requirements.

Despite its decline in popularity, the Waterfall software development methodology continues to find application, particularly in projects with well-defined and stable requirements, where upfront planning and predictability are valued. Let’s explore everything you need to know about the Waterfall approach and know if it’s suitable for your software development project.

What is the Waterfall Software Development model?

Waterfall method of software development is a linear and sequential SDLC approach to developing a software application.

Each project phase in the development lifecycle follows one another without overlapping, and must be fully completed before the next phase starts. So, it moves through design, implementation, testing, and maintenance in a strict order with the progress flowing in one direction – like a waterfall.

What are the Software Development Phases of Waterfall Model

Gathering initial requirements, design, implementation, testing, deployment and maintenance are 6 phases of waterfall software development. Let’s understand what is done in each steps and how are they related to each other in detail:

Initial Requirements Gathering

Business analysts (BAs) begin by collecting all the necessary requirements from stakeholders and define the project scope and specification. The BA team creates a detailed documentation to capture functional and non-functional requirements, to build a clear understanding of what the software must achieve. They must maintain thoroughness and clarity since changes after this point are difficult to manage.

System Design

Here the gathered requirements are translated into a structured plan. Software architects coordinating with the BA team create detailed architectural designs, specifying hardware and software requirements. They develop comprehensive diagrams such as data flow diagrams and entity-relationship models to build a blueprint for guiding developers in the implementation phase.

Implementation phase

Once the BA team clearly explains the requirements to the development team and the laters understands the architecture, the process of application development begins. This is a central phase of the waterfall model where software developers leverage a diverse set of tools comprising programming languages, frameworks etc. to build the application upon the devised architecture. Given the sequential nature of the process, the work executed here cannot be undone and it must go to the next stage.

Testing phase

Upon receiving the product from the implementation phase, the quality assurance (QA) team works with the assumption that whatever development has been executed in the previous phase is perfectly fine. They carry out different testing procedures including integration testing, system testing, and user acceptance testing to make sure that application delivers the performance as per the defined criteria.

Deployment phase

Now, it’s time to deploy the application considering that it has perfectly moved through all the previous phases of a project as there is no scope of going back. The application moves to the production environment. Next, the deployment team installs, configures, and runs it so it serves the intended purpose for end-users.

Maintenance

Once deployed, the maintenance team will conduct routine updates, bug fixes, and enhancements to keep the software operational and efficient. The maintenance phase also covers corrective measures for identified issues, adaptive updates for changes in the environment, and perfective improvements to optimize performance are all part of maintenance activities.

Advantages Of Waterfall Model

Waterfall development comes with its own advantages that still hold relevance in software development and why you must use the waterfall model.

Here are the 5 Benefits of Waterfall Methodology:

1. Simple & Easy
2. Clear goals and Milestones
3. Efficient Resource Planning & Management
4. Enhanced Accountability
5. Disciplined Approach

1. Simple & Easy

Each phase in the waterfall process follows a clear, logical order. Everyone understands her/his role and responsibilities, which is one big factor for clear communication among team members. The team understands that it needs to move sequentially, first completing the current phase and then moving to the next. So, the entire is driven by a mindset that perfectly executing a stage is critical, which simplifies the entire process of development.

1. Clear goals and Milestones

The model divides the project into distinct stages, each with specific milestones and deliverables. Clear goals means clear expectations set for the team. The completion of the requirements phase results in a detailed requirements document, while the design phase produces architectural and detailed design documents. These milestones help keep the track of the project’s advancement and achieving progress .

1. Efficient Resource Planning, Management, and Control

By knowing the specific requirements and deliverables of each stage in advance, project managers are in a position to allocate the right resources, such as personnel, equipment, and budget, exactly when they are needed. Optimally allocated resources while reducing wastage, makes sure that resources are available before moving on to the next phase. Since each phase has predefined deliverables and review processes, project managers can easily monitor progress and identify deviations from the plan.

1. Enhanced Accountability

Each phase has specific deliverables and deadlines which makes it clear who is responsible for each task. The requirement for transparency encourages team members to take ownership of their work because they are aware of how their contributions are critical to the project’s success.

1. Disciplined Approach

The upfront effort in gathering and documenting requirements pays off by minimizing the risks of scope creep and project overruns. So, if there is a government project or industry with stringent regulatory requirements, the Waterfall software development methodology is best suited as it provides a disciplined approach. With thorough validation at each stage, the model leads to a more predictable and controlled project outcome.

Disadvantages Of Waterfall Model

Waterfall software development, while once widely used, has several drawbacks that have led to its decreased popularity in favor of agile methodologies that offer multiple benefits.

Here are the 5 Major Drawbacks of Waterfall Model:

1. Inflexibility to Change
2. Late Testing Effort
3. Limited Customer Interaction
4. High Risk of Project Failure
5. Not Suitable for Complex or Large Projects

1. Inflexibility to Change

There is always an onus on the development team to first complete the ongoing phase before moving on to the next phase. As there is simply no scope to move back, it results in inflexibility to change. The model’s rigid nature thus makes it unsuitable for dynamic projects where requirements evolve or where the product must support rapid adaptation to market changes.

1. Late Testing Effort

Testing occurs in the fag end of the development lifecycle after the entire implementation process has been executed. However, it can lead to delayed detection of defects and issues. Consequently, identifying and addressing bugs becomes more challenging and resource-intensive. So, late detection of critical issues creates higher chances of disrupting project schedules.

1. Limited Customer Interaction

The model emphasizes formalized processes and documentation, often limiting direct customer involvement until the later stages of development. Lack of early and continuous customer interaction increases the chances of misalignment between the final product and customer expectations. Without regular feedback and validation throughout the development lifecycle, there’s a higher risk of delivering a product that fails to meet user needs.

1. High Risk of Project Failure

Any inaccuracies or misunderstandings in the initial requirements and design stages can propagate throughout subsequent phases and even result in project abandonment. The model’s lack of flexibility to accommodate changing requirements or unforeseen challenges is one risk creating factor, and results in missed opportunities and diminished project success rates.

1. Not Suitable for Complex or Large Projects

Complex or large-scale projects require iterative development and continuous feedback loops to manage uncertainties and mitigate risks effectively. But as the waterfall model requires defining all requirements upfront and adhering strictly to predefined stages it cannot be applied to large projects.

When to Choose Waterfall Software Development Model

A software development team should adapt the waterfall software development methodology if the project meets following criteria:

1. Known, Clear and Fixed Requirements
2. Predictable Project Environment
3. Small to Medium-sized Projects
4. Regulatory Compliance Requirements
5. Client Preference
6. Fixed-price Contracts

Let’s understand each criteria and situations in depth before choosing the waterfall model over other software development methodologies:

1. Known, Clear and Fixed Requirements

When you know that a project will follow a certain course as dictated, i.e. known and clear by its well defined requirements, you can confidently apply the waterfall model. In projects where the scope is stable and requirements are unchanging, i.e. fixed, the waterfall model provides a structured and efficient development workflow.

1. Predictable Project Environment

When the project environment is stable and predictable, the model’s linear nature offers several advantages. The stability allows for accurate planning and scheduling of each phase. For instance, if you are developing internal enterprise software development where the project environment is well-established and unlikely to change significantly during development, the model helps proceed methodically from one phase to the next without unexpected disruptions.

1. Small to Medium-sized Projects

Small and medium projects work with limited complexity and scope. For such projects, the waterfall model is best suited as it offers simplicity in project management and clear milestones, making it easier to manage and track progress. In these projects, there is less need for ongoing changes, and so the development team has a clear vision in front of it.

1. Regulatory Compliance Requirements

There are certain industries bound by stringent regulations and compliances. They want to build a software application against this strict backdrop where waterfall is the best choice. Regulatory compliance necessitates thorough documentation of processes, decisions, and validations. Waterfall mandates documentation at each stage and helps in demonstrating that the project has followed prescribed procedures and standards.

1. Client Preference

Sometimes clients themselves desire or are aware of the fact that their project needs to be executed with waterfall methodology. This can be due to multiple reasons: The client knows that its requirements are pretty stable and can be perfectly addressed in a sequential manner; it works in a regulated industry; the technical risks are minimal and there is no or minimal emphasis on rapid prototyping or experimentation; there is contractual obligation to use the approach.

1. Fixed-price Contracts

Amongst the various engagement approaches to software development, when you have chosen Fixed-price contracts, then Waterfall is a good choice for SDLC management. Fixed-price contracts specify deliverables and milestones, which can be well-mapped to Waterfall phases (e.g., design sign-off, development completion). Stakeholders can easily track progress and ensure that contractual obligations are being met within the agreed-upon timelines and budget.

Conclusion

Waterfall methodology remains one of the widely used SDLC approaches even today. Its structured approach and documentation-heavy nature promotes transparency and knowledge transfer among team members and stakeholders.

The above discussion might have well equipped you with the understanding of these dynamics and will help in when and how to apply Waterfall effectively in your software development projects.

In case you want to apply this model, reach out to our team and we will offer a roadmap and deliver a successful outcome.